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18th January 2005, 10:58 PM  #1 
diyAudio Member
Join Date: Jan 2005
Location: upstate NY

The Golden Rule?
Has anyone ever heard of the Golden Rule in speaker box building? I heard something about this and the formula is supposed to be 0.6 x 1.0 x 1.6 I am not sure what the multiplier is but I figure these three numbers are the height/width/depth when multiplied by another number. Could someone please help me with this one. I am going to be building a home theater system and need to figure out what size box I am going to need. The big question is If I am going to be putting two Tang Band W3881S into one enclosure what size does the inside measurments need to be for each speaker? If possible I would like to keep the depth around 4" and the enclosure taller than wider. Going for the slimmer look. Thanks for any advice that comes my way.
Jered22 
19th January 2005, 01:27 AM  #2  
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Join Date: Feb 2004
Location: Chicago area

Re: The Golden Rule?
Quote:
It is the "Golden Ratio". When a speaker box is built with its dimensions in this ratio internal standing waves are (supposed to be) minimized. So the numbers themselves are the multipliers. If your width for instance is 6 inches then the depth would be 10 inches and the height would be 16 inches. It actually doesn't matter with dimension is the height, width or depth.
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Sherman 

19th January 2005, 01:41 AM  #3 
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Join Date: Jan 2005
Location: upstate NY

So if this is true and I was building a box for a 3" driver and I wanted my box to be 3" in depth the box size should be 3"x10"x13" ? Is this correct? or 4" in depth it would be 4"x10"x14"? It seems to easy as if I am doing it wrong.
I am looking for the smallest box possible without compromising sound response for the Tang Band W3881S. I really need help! I am very new and don't understand the box dimensions. Please Help! I tried the freeware but that really does not help. I just need to know the internal cubic inches needed for one. Jered22 
19th January 2005, 01:54 AM  #4 
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No, the 3" driver looks like 3 x 5 x 8" and the 4" looks like 4 x 6.6 x 10" to me.

19th January 2005, 02:04 AM  #5 
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Join Date: Mar 2003
Location: London, Ontario, Canada

Wouldn't it be better to use prime numbers for ratios?
:)ensen.
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19th January 2005, 02:20 AM  #6 
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Join Date: Oct 2003
Location: Marin County, CA

http://mathworld.wolfram.com/GoldenRectangle.html
The math can look a bit daunting, but if you note the parts about what Euclid did with geometry, you'll get a pretty good feel for it. As others have said, make the length of a rectangle equal to 1.61 times it's side and you're on your way. Dig up a copy of "The Power of Limits" by Gyorgy Doczi for a good time. It starts with the appearance of the divine ratio in nature and art, and goes outward from there. How come math was never this fun / useful / interesting in school?
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19th January 2005, 02:28 AM  #7  
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Quote:
As far as why it's been thought of as a good idea to use in audio, I think that's because you might have a 500hz standing wave between two panels, but with that ratio you will not have a standing wave at 250 or 1000 hz between two other panels. If your box is small enough that the smallest wavelength in its passband is greater than 4 times the longest internal dimension (say, corner to corner), you shouldn't have any trouble with internal standing waves. Another way to fight internal standing waves is to use trapezoids, so the walls aren't parallel. This prevents large flat areas from being of a constant equal distance. Here's a site with more information about the golden ratio, but I think they overhype it just a little bit. http://goldennumber.net/ Other ways to fight standing waves include fibrous stuffing material (polyfill from walmart) in a regular tapered box, or in a tapered terminated tube like the B&W nautalus. So, I think that's why (other than looks) that you hear about the golden ratio in speakers. If anyone has more info, I'd be eager to hear it 

19th January 2005, 03:56 PM  #8  
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Join Date: Jun 2003
Location: Chamblee, Ga.

Quote:
Quote:
So about all you can do if one dim is 2.5" is to multiply the longest internal dim you can tolerate by 2.5 (or other dim) and divide it into the Vb to find the width. Again, assuming a 0.75" thick baffle, the vent would be a 2" diameter hole. Add stuffing to 'taste'. GM
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19th January 2005, 04:07 PM  #9  
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Join Date: Jun 2003
Location: Chamblee, Ga.

Quote:
GM
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19th January 2005, 04:18 PM  #10 
diyAudio Member
Join Date: Oct 2003
Location: L.A., CA

Actually, there are many 'golden ratios'. The idea behind them is that the product of all the dimensions is equal to 1. Notice that .6x1x1.6=1 and .8x1x1.25=1 and so on.
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